GREEN BAY - Cassie Nygren knew Jennifer Skeen was pregnant and knew the heroin she sold her was laced with often deadly Fentanyl, a prosecutor said Thursday.

Nygren and her boyfriend, Shawn M. Gray, will be formally charged in Brown County Circuit Court next week with helping to cause the drug-related death of Skeen and her unborn child, Brown County Assistant District Attorney Wendy Lemkuil said.

The two suspects were in court Thursday, but prosecutors were still poring over investigative findings and weren't prepared to file charges. Instead, a probable cause hearing was held at which Lemkuil laid out reasons why the two should be held on $50,000 cash bonds until charges can be readied. That'll be Oct. 19 for Nygren and the next day for Gray.

Nygren, 28, and Gray, 33, provided the heroin that killed Skeen and her unborn baby on June 2 at their home on South Webster Avenue in Allouez, Lemkuil said.

Another resident of the house told investigators Skeen and Nygren met outside the home the previous night, supposedly to "exchange baby bottles," Lemkuil told the court. Nygren was aware Skeen was about 6 months pregnant and later admitted she and Gray had been dealing heroin that apparently contained Fentanyl, because she and Gray had themselves become ill from using some of the drug, Lemkuil said.

Nygren also told a confidential informant to whom she sold heroin that she and Gray had to administer Narcan, a heroin antidote, to several of their heroin customers, Lemkuil said.

Nygren herself was pregnant when she was kicked out of the Brown County Drug Court treatment program about a year earlier for using drugs, Lemkuil said. Although Nygren eventually was cooperative with police investigating Skeen's death, she told them she had relapsed from her treatment just once, when, in fact, Drug Court records showed she had relapsed and used heroin several times in the year in which she was enrolled in the program, Lemkuil said.

When responding to Skeen's death, investigators initially only knew someone named "Cassie" was involved, Lemkuil said. But probing Skeen's social media pages and cellphone led them to Nygren, she said. Investigators used a confidential informant to make controlled purchases of heroin from the couple as part of the investigation, Lemkuil said.

A search conducted at the couple's home on Loretta Lane in Green Bay turned up heroin, paraphernalia and what appeared to be ledgers, Lemkuil said.

Police arrested them Tuesday. They tried to stop their car in Bellevue, and Gray rammed a vehicle and sped off, Lemkuil said. Police, knowing Nygren's 14-month-old son was in the car, broke off the chase but caught them outside the car a short time later, Lemkuil said.

Gray faces not only homicide charges in the two drug deaths but also a variety of charges alleging he was dodging sex offender registration requirements. Lemkuil said he paid a friend in Michigan to accept Gray's mail to disguise the fact that Gray was living in Green Bay, Lemkuil said.

Gray(Photo: Courtesy of Brown County Jail)

Nygren is facing possible charges of two counts of first-degree reckless homicide-deliver drugs, delivery of heroin, child neglect and maintaining a drug trafficking place. She also faces a handful of possession charges.

The child neglect charge involves her dealing of heroin with her child present, according to the Brown County Sheriff's Office.

Gray also faces two counts of reckless homicide, two of bail-jumping, a charge of second-degree recklessly endangering safety for the car flight, and then charges related to failing to comply with requirements of sex offender registry. He also was cited for five traffic-related offenses.

Nygren, the daughter of state Rep. John Nygren, R-Marinette, was featured in media reports in June 2014 after her own brush with a near-fatal heroin overdose.

After her release from a two-year prison term in June 2014, she became Marinette's “street team coordinator” for Rise Together, a state group that tries to educate and mentor young addicts.

But she ended up with another conviction in 2015 of drug possession. This time she was admitted to Brown County Drug Court, a program started in 2009 to help participants fight addiction through phases of treatment and supervision. It works much like probation but is stricter, with a rigid schedule of drug testing, office visits and weekly court appearances.

Her father, John Nygren, has authored numerous bills supportive of drug treatment efforts.

He issued a statement Wednesday expressing condolences to Skeen’s family and promising to support his daughter.